Abstract

This paper addresses the structures and ), whereMis a nonstandard model of PA andωis the standard cut. It is known that ) is interpretable in. Our main technical result is that there is an reverse interpretation of in ) which is ‘local’ in the sense of Visser [11]. We also relate the model theory of to the study of transplendent models of PA [2].This yields a number of model theoretic results concerning theω-models and their standard systems SSy, including the following.•$\left \prec \left$if and only if$M \prec K$and$\left} \right) \prec \left} \right)$.•$\left} \right) \prec \left} \right)$if and only if$\left \prec \left$for someω-saturatedM*.•$M{ \prec _{\rm{e}}}K$implies SSy = SSy, but cofinal extensions do not necessarily preserve standard system in this sense.• SSy=SSy if and only if ) satisfies the full comprehension scheme.• If SSy is uniformly defined by a single formula, then ) satisfies the full comprehension scheme; and there are modelsMfor which SSy is not uniformly defined in this sense.